1. Mixtures and Solutions

2. Mixtures, elements, compounds
Scientists like to classify things.
One way that scientists classify matter is by its composition.
Based on composition, matter can be classified into: Elements, Compounds, and Mixtures.

4. By asking these questions scientists can classify matter into:
Elements – simplest form of pure substance. They cannot be broken into anything else by physical or chemical means.
Compounds – pure substances that are the unions of two or more elements. They can be broken into simpler substances by chemical means.
Mixtures – two or more substances that are in the same place, but their atoms are not chemically combined and can be separated by physical means. The substances in a mixture retain their individual properties.
Solutions – a special kind of mixture where one substance dissolves in another.

5. Mixtures A mixture is a combination of two or more components that
are NOT chemically combined,
and retain their identities.
Mixtures can be physically separated.
The identities of the substances DO NOT change in a mixture.

6. Mixtures
When a mixture’s components are easily recognizable, such as pizza, it is called a heterogeneous mixture.
Example: Suspensions
In a homogeneous mixture such as chocolate milk, the component particles cannot be distinguished, even though they still retain their original properties.
Example: Colloids and Solutions

7. Homogeneous Mixtures A mixture that appears to be the same throughout.
It is “well mixed.”
The particles that make up the mixture are very small and not easily recognizable.
Homogeneous mixtures can be solutions or colloids.

8. Examples of heterogeneous mixtures
Sand and pebbles
Oil and water
Powdered iron and powdered sulfur

9. Heterogeneous Mixtures
Mixtures can be solid.
Granite is a heterogeneous mixture.

10. Examples of homogeneous mixtures
Milk, toothpaste, and mayonnaise are homogeneous
mixtures. They are also colloids.

11. Page 393

12. Types of Mixtures There are three types of mixtures: Suspensions
Colloids
Solutions

13. Suspensions A mixture in which particles of
a material are dispersed through-
out a liquid or gas but are large
enough that they settle out.
Particles are insoluble, so they DO NOT dissolve in the liquid or gas.
Particles can be separated using a filter.
Examples:
Salad dressing
Medicines that say
“shake well before use”
Animation of the particles in colloid, solutions, and suspensions:

14. Types of Mixtures There are three types of mixtures: Suspensions
Colloids
Solutions

15. Colloids
A colloid is a mixture in which the solute is broken down into pieces that are too small to see with the naked eye, but are large enough to interfere with visible light. As a result, colloids are cloudy.
In a colloid the particles are mixed together but not dissolved.
The particles are relatively large and are kept permanently suspended.
The particles are dispersed throughout but are not heavy enough to settle out.
Animation of the particles in colloid, solutions, and suspensions:

16. Colloids - A colloid will not separate upon standing.
The particles are not dissolved!
The particles are constantly colliding, and this allows a colloid to scatter light – thus colloids often seem cloudy.
Milk is an emulsified colloid of liquid butterfat globules dispersed within a water-based solution.

19. Types of Mixtures There are three types of mixtures: Suspensions
Colloids
Solutions

20. Solutions
A solution is a type of homogeneous mixture formed when one substance dissolves in another.
A solution always has a substance that is dissolved and a substance that does the dissolving.
The substance that is dissolved is the solute and the substance that does the dissolving is the solvent.
The particles of the solute separate from each other and become surrounded by particles of the solvent.
Animation of Salt dissolving in water:

21. Solutions A solution may be liquid, gaseous, or solid.
A mixture that appears to be a single substance but is composed of particles of two or more substances that are distributed evenly amongst each other.
A solution may be liquid, gaseous, or solid.
Examples of solutions
Liquid - seawater
Gas - air
Solid - alloys

22. Solutions
Dissolving – The process in which particles of substances separate and spread evenly amongst each other.
Solute – substance that is dissolved.
A solute is soluble, or able to dissolve.
Solvent – substance in which solute is dissolved.
A substance that is insoluble is unable to dissolve, forms a mixture that is not homogeneous, and therefore NOT a solution.

23. Metals dissolved in metals are called alloys.
Types of solutions
Solute
Solvent
Example
Gas
Air (oxygen in nitrogen)
Liquid
Soda water (carbon dioxide in water)
Solid
Ocean water (salt in water)
Solid
Alloys, Gold jewelry (copper in gold)
Metals dissolved in metals are called alloys.

24. Particles in Mixtures and Pure Substances
So, in simplest terms, the difference between solutions, colloids and suspensions is the size of the solute particles.

25. How does a solution form?

26. How does a solution form?
A solution forms when particles of the solute separate from each other and become surrounded by particles of the solvent.

27. How does a solution form? Animation and Video
Animation of Salt dissolving in water:
How Water Dissolves Salt – video – Dissociation of salt -

28. is made of two parts the solvent and the solute
Solutions
is made of two parts the solvent and the solute

29. is the liquid that does the dissolving.
Solvent
is the liquid that does the dissolving.

30. the solid that dissolves in the solvent
discover.edventures.com/.../s/solute/support.gif

31. Ocean water is a solution

32. The universal solvent: Water

33. Water as a solvent Many liquid solutions contain water as the solvent.
Ocean water is basically a water solution that contains many salts.
Body fluids are also water solutions.

34. Air is a solution of oxygen and other gases dissolved in nitrogen

35. Alloys – a mixtures of solid metals.
Stainless steel is a mixture
of iron and chromium.
Brass is an alloy of copper
and zinc.
Bronze is an alloy consisting primarily of copper, commonly with about 12% tin and often with the addition of other metals (such as aluminum, manganese, nickel or zinc) and sometimes non-metals or metalloids such as arsenic, phosphorus or silicon.

36. Solutes and Conductivity
Ionic compounds in water conduct electric current, but a solution of molecular compounds (neutral) may not.
Pages 401

37. Effects of Solutes
Solutes raise the boiling point of a solution above that of the solvent.
Page 401 in the book

38. Effects of Solutes
Solutes lower the freezing point of a solution below that of the solvent alone.
Page 401 in the book

39. Techniques for Separating Mixtures
Distillation
Magnetism
Centrifugation
Evaporation
Filtration
Chromatography
Decanting

40. Techniques for Separating Mixtures
Distillation -
separates a mixture based on boiling points of the components.
Examples :
saltwater
crude oil into gasoline and kerosene
Video:

41. Techniques for Separating Mixtures
Distillation -

42. Techniques for Separating Mixtures
Magnetism – Magnetic attraction separates iron or other magnetic materials from
non-magnetic objects.

43. Techniques for Separating Mixtures
Centrifugation - spins and separates mixtures according to densities.
Centrifuge
Process:
Density Gradient Centrifugation - Isolate Mononuclear Cells from Whole Blood (Ficoll or Lymphoprep)

44. Techniques for Separating Mixtures
Evaporation
Separates mixtures by letting some of the components turn into gas, leaving the solid components behind.
It can be done quickly with gentle heating or left out to 'dry up' slowly in 'open air'.
The solid will almost certainly be less volatile than the solvent and will remain as a crystalline residue.
Evaporation is often followed by crystallization.

45. Techniques for Separating Mixtures
Filtration – separates solids from liquids by pouring the mixture through a filter. The solids are collected in the filter, while the liquids go through into another container.
Video:

46. Techniques for Separating Mixtures
Chromatography
separates a mixture of chemicals, which are in gas or liquid form, by letting them creep slowly past another substance, which is typically a liquid or solid
Tutorial: Paper and Thin Layer Chromatography | The Chemistry Journey | The Fuse School
CHROMATOGRAPHY: Technique for separating mixtures of products (Animation)

47. Decanting (Decantation)
Techniques for Separating Mixtures
Decanting (Decantation)
a process for the separation of mixtures by removing a layer of liquid, generally one from which a precipitate has settled.
The purpose may be either to produce a clean decant, or to remove undesired liquid from the precipitate (or other layers).

49. Separating Mixtures
Take out your Chapter 11 packet
Work on page 395

50. January 13th, 2016
Do NOW
Take your Chapter 11 out (you should have it with you because you tore it out yesterday)
Now, do page 395.

51. Page 395

52. Solubility

53. Solutes and Conductivity
Ionic compounds in water conduct electric current, but a solution of molecular compounds (neutral) may not.
Pages 401

54. Effects of Solutes
Solutes raise the boiling point of a solution above that of the solvent.
Page 401 in the book

55. Effects of Solutes
Solutes lower the freezing point of a solution below that of the solvent alone.
Page 401 in the book

56. Solubility
A measure of how much solute can dissolve in a solvent at a given temperature.

57. Solubility
The solubility - A measure of how much solute can dissolve in a solvent at a given temperature.
Solubility is usually expressed in grams of solute per 100 ml of solvent (g/100ml)
Can help identify a substance.
Three (3) methods that affect solubility
Mixing, stirring, or shaking
Heating
Crushing or grinding (particle size)

58. Concentration the ratio of solute to solvent
woelen.scheikunde.net/.../exp0012.jpg

59. Concentrated
solutions with a high ratio of solid material (solute) to liquid (solvent)
(strong)

60. Dilute
solutions with a low ratio of solid material (solute) to liquid (solvent)
woelen.scheikunde.net/.../exp0012.jpg
(weak)

61. Saturated Solution
solute dissolves in a solvent until no more will dissolve
(additional material may sit at the bottom) 

62. Factors Affecting Solubility
Pressure
Type of solvent
Temperature
Particle size

63. Factors Affecting Solubility
Pressure - As pressure increases the solubility of a gas solute in a liquid solvent increases.

64. Factors Affecting Solubility
Type of solvent
For liquid solutions:
“like likes like”
Ionic and polar compounds usually dissolve in very polar solvents.
Nonpolar compounds do not usually dissolve in very polar solvents, but they will dissolve in nonpolar solvents.

65. Factors Affecting Solubility
Temperature - For most solid solutes, solubility increases and temperature increases. - Unlike most solids, the solubility of a gas decreases as temperature increases.

66. Particles in Mixtures and Pure Substances
The diagram shows five particles of elements and compounds. Each circle represents an atom of an element. Match the pictures A to E to the following questions.
Diagram
(a) Which particle picture represents a mixture of two compounds? ____ (b) Which particle picture represents a pure compound? ____ (c) Which particle picture represents a mixture of an element and a compound? ____ (d) Which particle picture represents a pure element? ____ (e) Which particle picture represents a mixture of two elements? ____ (f) Which particle picture could represent pure water? ____ (g) Which particle picture could represent something dissolved in water? ____

67. Particles in Mixtures and Pure Substances
So, in simplest terms, the difference between solutions, colloids and suspensions is the size of the solute particles.

68. Particles in Mixtures and Pure Substances
Methods for separating Mixtures:
Animation of the particles in colloid, solutions, and suspensions:

69. Particles in Mixtures and Pure Substances
Animation:

70. Class Assignment
Work on pages

71. The diagram shows five particles of elements and compounds
The diagram shows five particles of elements and compounds. Each circle represents an atom of an element. Match the pictures A to E to the following questions.
(a) Which particle picture represents a mixture of two compounds? ____ (b) Which particle picture represents a pure compound? ____ (c) Which particle picture represents a mixture of an element and a compound? ____ (d) Which particle picture represents a pure element? ____ (e) Which particle picture represents a mixture of two elements? ____ (f) Which particle picture could represent pure water? ____ (g) Which particle picture could represent something dissolved in water? ____